(Add details of South Korean inspections)
By David Shepardson and Jamie Freed
WASHINGTON, Feb 22 (Reuters) – Damage to a fan blade on a failed engine on a United Airlines Boeing 777 flight is consistent with metal fatigue, a preliminary assessment shows, the chairman of the plane crash investigator said on Monday. from the United States.
The Pratt & Whitney PW4000 engine failed with a “loud thud” on Saturday four minutes after takeoff from Denver, National Transportation Safety Board (NTSB) Chairman Robert Sumwalt told reporters after initial analysis. from the flight data recorder and the cockpit voice recorder.
There was minor damage to the body of the aircraft, but no structural damage, he said.
He said it was unclear if the incident is consistent with an engine failure on a different United flight to Hawaii in February 2018 that was attributed to a fatigue fracture in a fan blade.
“What is important is that we really understand the facts, the circumstances and the conditions surrounding this particular event before we can compare it to any other event,” Sumwalt said.
The engine that failed in the 26-year-old Boeing Co777 and dropped parts in a Denver suburb was a PW4000 used in 128 aircraft, or less than 10% of the world’s fleet of more than 1,600 delivered 777 wide-body aircraft.
In another incident on Japan Airlines (JAL) 777 with a PW4000 engine in December 2020, Japan’s Transport SafetyBoard reported finding two damaged fan blades, one with a metal fatigue crack. An investigation is ongoing.
The focus is more on engine maker Pratt and analysts expect a small financial impact on Boeing, but the PW4000 woes are a new headache for the aircraft maker as it recovers from the 737 MAX crisis, much more. serious. Boeing’s narrow-body flagship aircraft was grounded for nearly two years after two fatal accidents.
The United motor’s fan blade will be examined Tuesday after being transferred to a Pratt lab where it will be examined under the supervision of NTSB investigators.
The U.S. Federal Aviation Administration (FAA) said on Monday that it had already been evaluating whether to adjust fan blade inspections in the wake of the December incident in Japan, after reviewing maintenance records and conducting an examination. metalworking of the fragment of the fan blades.
Boeing recommended that airlines suspend use of the planes while the FAA identified an appropriate inspection protocol and Japan imposed a temporary suspension of flights.
Pratt & Whitney, owned by Raytheon Technologies Corp., recommended that airlines increase inspections at a plant that is under review by the FAA, sources with knowledge of the matter said. Pratt did not immediately respond to a request for comment.
The FAA has said it plans to issue an emergency airworthiness directive soon that will require intensified inspections of the fan blades for fatigue.
“United Airlines has grounded all affected aircraft with these engines, and I understand that the FAA is also running very quickly, as has Pratt & Whitney reiterated or revised a service bulletin,” Sumwalt said. “It appears that action is being taken.”
In March 2019, after the United 2018 engine failure attributed to fan blade fatigue, the FAA ordered inspections every 6,500 cycles. A cycle is a take off and a landing.
South Korea’s Transportation Ministry said Tuesday that it had told its airlines to inspect fan blades every 1,000 cycles following Pratt’s instructions after the United incident.
Sumwalt said the United incident was not considered a total engine failure because the containment ring contained the parts while they were flying.
The NTSB will investigate why the engine hood detached from the plane and also why there was a fire despite indications that the engine fuel had gone out, Sumwalt added.
Industry sources said that although the engine is manufactured by Pratt, the hood or shell is manufactured by Boeing. Boeing referred their questions to the NTSB.
Almost half of the global fleet of PW4000-equipped Boeing777s operated by airlines such as United, JAL, ANAHoldings, Korean Air and Asiana Airlines had already been on the ground amid a drop in travel demand due to the coronavirus pandemic ( David Shepardson’s report in Washington and Jamie). Freed inSydney; additional reporting from Tracy Rucinski in Chicago, JoyceLee in Seoul and Tim Hepher in Paris; edited by Kim Coghill and Gerry Doyle)